sometimes after my car is warmed up and i put the car in park it revs up and dworn from 1 to 2 by itself anyone know what this might be.

 

up and down*

 

O2 sensor or Adjust throttle cable.

 

First check your coolant level, if it's okay, then you may have some crap stuck in your fast idle valve. It's bolted to the intake manifold and has two hose lines coming out, and a brass plate on the top. open up the top and try blowing it out with compressed air.